This invention relates to tricyclic 3-keto derivatives of 6-O-methylerythromycin A. The compounds of this invention are useful as antibiotic agents in mammals, including man, as well as in fish and birds. The compounds of the present invention are broad-spectrum macrolide antibiotics that are effective against infections caused by certain gram-positive and gram-negative bacteria as well as protozoa.
Macrolide antibiotics are known to be useful in the treatment of a broad spectrum of bacterial infections and protozoa infections in mammals, fish and birds. Such antibiotics include various derivatives of erythromycin A such as azithromycin which is commercially available and is referred to in U.S. Pat. Nos. 4,474,768 and 4,517,359, both of which are incorporated herein by reference in their entirety. Additional macrolides are referred to in U.S. patent application Ser. No. 60/063676, filed Oct. 29, 1997 (Yong-Jin Wu), U.S. application Ser. No. 60/063161, filed Oct. 29, 1997 (Yong-Jin Wu), U.S. application Ser. No. 60/054866, filed Aug. 6, 1997(Hiroko Masamune, Yong-Jin Wu, Takushi Kaneko and Paul R. McGuirk), all of which are incorporated herein by reference in their entirety. Like azithromycin and other macrolide antibiotics, the novel macrolide compounds of the present invention possess activity against various bacterial infections and protozoa infections as described below.